First of all, a method of controlling an operation of a device according to a related art is explained as follows.
According to a related art, a reed switch is used to control an operation of a device.
The reed switch is a sort of a magnetic switch including a pair of reeds, which are ferromagnetic and elastic substance to be well attracted to a magnet, put in a small glass tube charged with inert gas to prevent corrosion of the reeds.
The operational control using the reed switch includes the following steps.
First of all, a magnet is placed in the vicinity of the reed switch. If the magnet is located at a central part of the reed switch, induction line of the magnet is formed from a north pole to a south pole. In this case, the induction line passing through the reeds magnetizes tips of the reeds into the north and south poles, respectively. So, an attractive force is generated between the reeds to make them come into contact with each other, whereby the device is turned on.
Meanwhile, if the magnet is placed distant from the reed switch, the magnetized reeds return to their original states to be separated from each other. So, the device is turned off.
However, in the above-explained related art, since additional current is consumed for the operational control by the reed switch, a life span of an internal battery is reduced.